得到指定日期【月初和月末】

// 得到指定日期
// [2018-10-12]
public function GetMonth($date){
    $firstday = date("Y-m-01",strtotime($date));
    $lastday = date("Y-m-d",strtotime("$firstday +1 month -1 day"));
    return ['startime'=>$firstday,'endtime'=>$lastday];
}